Using a positional cloning strategy combined to a candidate gene approach, the otoferlin gene (OTOF) has been identified, as responsible for neurosensory nonsyndromic recessive deafness, DFNB9. The OTOF gene codes for the protein: otoferlin, which is present in the inner ear and brain. The exact function of otoferlin is not yet known, but it appears to be essential for normal hearing.